Septic drain line above ground after dirt settled.

When my septic system was replaced just prior to buying my house, about a year and a half ago, they used the same drain pipe hole in the foundation that used to go to the old system, replacing all of the old cast iron drains in the house with PVC.

After a year and a half, the dirt has settled a few inches around where the pipe leaves the house so now the top of the pipe is exposed outside. Obviously I'll have to cover that just to keep the PVC from being damaged but I'm wondering what about freezing? The frost line around here (southern Rhode Island) is 40" I believe -- there's no way I can put 40" of dirt on top of that, the dirt would be up to my windowsills. But the old drain was in the same location and aparently it wasn't a problem then -- do drain lines not freeze as easily as supply lines or something? Can I just put 6 inches of dirt over it or is more drastic action required?

I attached a picture that shows the house foundation on the right and the pipe running under the grass through the middle right to left (the green thing is a temporary downspout extender).

Is a running back, still a running back after he is tackled? Have you ever had to tackle a running toilet, (they can be elusive)? You have to get into calculus to determine the exact point where "running" water stops and becomes "frozen" water, but a river can freeze over and then the water is still running but the layer that is contact with the "unrunning" frozen water will defect and join the frozen stuff, (probably because of fatigue and laziness).